Technical Abstract:
During conversion of hides into leather, some hide constituents undergo changes and removal. Among those are decorin, biglycan, sulfated glycosaminoglycan (SGAG) and collagen. Properly monitoring the removal of the predominant and best understood proteoglycan of skin, decorin, was the focus of this work. An ELISA method was improved by dialyzing the guanidine×HCl-extracted proteins in the presence of collagenase, allowing us to obtain a more manageable sample with uniform background and in turn more reliable analytical data. ELISA results on the depletion of decorin in intact hide samples were evaluated and compared among the different parts of bovine hide before and after dialysis. There was a clear difference between undialyzed and dialyzed samples of raw intact hide, whereas after the tanning treatments, the available decorin content was significantly the same from different parts. The amount of decorin that was removed from each area of the hide (shoulder > butt > belly), after processing the hide samples using the standard USDA tanning procedure, was directly proportional to the initial amounts. The final available decorin remaining per gram of intact hide in leather (bated samples) was significantly the same in all parts. Based on the dialyzed samples, there was about a 70-78% reduction of available decorin content from raw hide to bated hide samples compared to ~90% in undialyzed samples. The results followed more closely the trend of the SGAG (carbohydrate part of decorin) content determination previously reported by this group, where about a 75% drop was observed from the initial available SGAG content in raw hide to bated hide samples.